Methods and apparatus for automatically guiding an airplane or the like



Nov. 3, 1964 1. B. JONES METHODS AND APPARATUS FOR AUTOMATICALLY GUIDING AN AIRPLANE OR THE LIKE 4 Sheets-Sheet 1 Filed DeC. 6. 1947 u mv Nw 3 w.

om. mw ww vw ON Rm, Wm.

3mm/V110@ James Byra/f Jones wwew J. B. JONES Nov. 3, 1964 METHODS AND APPARATUS FOR AUTOMATICALLY GUIDI-NG AN AIRPLANE OR THE LIKE 4 Sheets-Sheet 2 Filed Dec. 6. 1947 NSW mmmwmw l Sm, s s@ ism,

eff Ruda/ef gmc/who@ J. B. JONES METHODS AND APPARATUS FOR AUTOMATICALLY Nov. 3, 1964 GUIDING AN AIRPLANE OR THE! LIKE 4 Sheets-Sheet 3 Filed Dec. 6. 1947 V W e T. i @i T m @M www Nov. 3, 1964 J. B. JONES 3,155,969

METHODS AND APPARATUS FOR AUTOMATICALLY GUIDING AN AIRPLANE 0R THE LIKE Filed Dec. 6. 1947 4 Sheets-Sheet 4 H 'Q NN i L "WS Q Q m Q 3 Q s Y 3J *g 0 'o k l V) o tu wm v QS t n k Jam es .Eyre/7 daf/e5 www@ 75 insam zaneol/s Radar Pfc/(up United States Patent O 3,1.5559 METHDS AND APPARJEUS CAlJiJY fG-UlDlN-G AN AilllAlJE @it 'EHR llilll .lames Byron liones, Stamford, Conn., assigner to Goodyear Aerospace Corporation, a corporation of Delaware Filed Dee. o, i947, Ser. No. Whll 12 Claims. (Cl. 3437) This invention relates to methods and apparatus for controlling and guiding vehicle movement, and, more particularly, is concerned with automatic or substantially automatic methods and apparatus for guiding aircraft and like bodies between points on the earths surface.

Automatic pilots are well known for use in controlling the movement of a torpedo, or for guiding and controllin the night of an airplane, but such known devices, while having certain advantages and functions, tail to guide and control a vehicle or body with sufficient accuracy, particularly when the vehicle or body moves over relatively long distances.

lt is the general obiect of the present invention to avoid and overcome the foregoing and other difficulties of and objections to known methods and apparatus for automatically guiding and directing vehicles and bodies by the provision of improved methods and apparatus for controlling the ilight of aircraft, the movente? of boats, submarines, torpedos, and the like, with a greater accuracy and in a more positive manner than has heretotore been possible.

Another object of the invention is to provide auto matic mechanism and methods for guiding a vehicle or other body along a given path and to keep the vehicle or body on this path by comparison ot a series oi instantaneous pictures of the path with a previously provided picture of the path over which the vehicle or body is to be moved, and to automatically correct the movement of the vehicle or body to the previously selected path.

Another object of the invention is the provision or" methods and apparatus for matching a known radar strip map with an instantaneous radar image, followed by the establishment of corrective factors which will bring the vehicle or body to substantially center the instantaneous radar image on the strip radar map.

The foregoing objects of the invention, and other objects which will become apparent as the description proceeds, are achieved by the provision in combination, of a strip lm bearing a map of a stretch or terrain over which a body is to move, motor means for unwinding the lm, means for presenting an instantaneous image of the terrain over which the body is moving, said instantaneous image being superimposed relative to the map image, means for effecting periodically repeated scanning movement between the superimposed images, means for indicating substantially a match between the images, and means for controlling a direction of movement of the body in response to the position of match of the images.

For a better understanding of the invention, reference should be had to the accompanying drawings, wherein:

FIG. l is a schematic assembly view of one embodiment of apparatus incorporating the principles or the invention;

FIG. 2 is a diagrammatic View of the type of scanning between the map image and the instantaneous image;

FIG. 3 is a graph illustrating the matching of the map and instantaneous images;

FIG. 4 is a diagrammatic illustration of one type of guided tiight or movement;

FIG. 5 is a view similar to FIG. 4 but illustrating another type of guided movement;

ICC

FG. 6 is an enlarged fragmentary view of a portion of the apparatus incorporated with FIG. l; and

FiG. 7 is a view similar to FIG. 1, but illustrating another embodiment of the apparatus incorporating the principles of the invention.

lt will be recognized that the invention herein illustrated and described may be employed in conjunction with the controlling and guiding of vehicles, bodies, missiles, and the like, of a wide variety of types, and used for various different purposes. For example, the features of the invention can be utilized in conjunction with submarines, surface vessels, rockets, and the like, but the invention is primarily concerned with the controlled ight of an aircraft driven by jet propulsion or other means, and, accordingly, the invention has been so illustrated and will be so described.

Furthermore, it is to be understood that the words map, and iniage, and the like, employed in the specilication and claims, are intended to include optical, acoustical, radar or other pictures, maps, or images. However, one best known embodiment of the invention is concerned with radar maps and instantaneous radar images, and the invention has been illustrated accordingly and will be so described.

in utilizing the invention with an airplane, or other type of aircraft, and to control the ilight of the airplane over rather widely separated points of the earths terrain, it is advisable to incorporate in the airplane the usual and known automatic pilot mechanism, the apparatus and methods of the invention functioning to provide the final, or it might be said, Vernier control to exactly keep the airplane on course, but with the automatic pilot functioning to substantially overcome normal disturbing influences, such as up or down drafts, sudden gusts, and the like. Also, the automatic pilot mechanism should function to keep the airplane parallel to the desired course. However, it may be noted that many of the advantages of the invention are realized without the automatic pilot, and the invention is not to be limited to operations in association with an automatic pilot.

in accord with the principles of the invention, there is incorporate-d in the airplane in addition to the conventional automatic pilot mechanism, an instantaneous radar pick-up. ln FlG. 1 of the drawings, the numeral 1 indi* cates generally oscilloscope having detlector plates 2, electron generator 3, screen 4, and the usual lead-in means and associated apparatus (not shown) to impose upon the screen d an instantaneous radar image of the terrain over which the airplane is passing. Preferably, but not necessarily, incorporated with the oscilloscope is a lens system 5 and a light source 6, so that with thev oscilloscope envelope being shaped as shown and with the screen d inclined, as illustrated, and being of the dark-trace type, a light beam will be thrown through screen t to direct the image thereon against a strip of film 7.

it will be understood that if a projection system (lens 5 and light o) is used with the screen 4i, the screen must be of the dark-trace type described (disclosed, for eX- arnple, in British Patent No. 536,720) and the image on the screen will have areas verging from transparent to opaque. 0n the other hand, it the lens 5 and light 6 are not used then the screen l is conventional, that is of substantially uniorm` opaqucness and having various portions glowing to dark controlled by the usual electron iiow. The system illustrated and described in FIG. l can be used with a conventional oscilloscope screen 4, with the radar image on the screen matching with the map image on the lm '7 as determined by the photoelectric means behind the lm '7, all as hereinafter described.

The film 7 bears a strip radar image or map of the terrain over which the airplane is to fly, and the strip is continuously unrolled from one spool 8 and is wound up-ona second spool 9, the spool 9 being driven by a motor 10 whose speed is controlled by varying a rheostat 11, in a manner to be hereinafter described.V Electric leads 12 extend to a suitable power source. By a strip radar image or map is means a panoramic reproduction of the radar picture of the terrain over which the airplane is to fiy. A conventional strip map in panoramic formi of an automobile route is well understood. The strip radar image or map is broadly similar but shows a radar picture in panoramic formptaken from a selected distance from the ground and illustrating the terrain path iiow by or to be flown by the airplane.

' The instantaneous radar image on the screen 4, 'and the strip radar image on the film 7, are adapted to be relatively moved to effect a match of the images. This relative movement can be effected in a number of different ways. One mianner of achieving the matching action is to mount the spools 8 and 9, and the motor 10, on a frame 13, which is carried at one end of a rod 14, the other end of the rod being provided with an adjustable, resiliently positioned, counterweight 15. Positioned intermediate the frame 13 and the counterwe-ight 15 is a pivotal support for the rod 14, the numeral 16 indicating a bracket having a horizontal p-ivotal connection 17 with the rod 14, and with the bracket 16 being mounted for rotation about a vertical pivot 18 carried in a fixed plate 19.

The lm strip 7 is adapted to be given a scanning movement relative to the screen 4, and while this scanning movement may be accomplished by various mechanisms, one convenient manner of achieving the desired scanning action is to provide a cam plate 20 adjacent the resiliently-positioned, counterweighted end of the rod 14, and to have this end of the rod carry a cam follower 21 which rides in a spirally cut cam groove on the side face of the plate 20. Reference should be had to FIG. 2 of the drawings in which the line 22 indicates a typical shape in which the cam groove may be cut in the side of the circular plate 20. The plate 29 is secured to the end of a shaft 23 which is journaled in bearings 24, the shaft being' adapted to be rotated by a reversible motor 25.

The shaft 23 is formed with a helical groove 26, and slidably mounted upon the shaft 23 is'a block 27 which carries a cam follower which fits down into the groove 26. Thus, as the shaft 23 is rotated, the block 27 will move from one end to the other of the shaft. At the same time the cam follower 21 riding in the cam slot 22 in the side of the circular plate 20 Will cause the film strip 7 to be given a spiral scanning movement with relation to the screen 4. As the block 27 begins to reach the end of its movement upon the shaft 23, and at the same time with the cam follower 21 beginning to reach the end of its movement in the cam track 22 of the circular plate 20, a stop 28 mounted on the bearing 24 will strike a switch arm 29 of a switch carried on the block 27 to throw the switch in the opposite direction and reverse the drive of the electric moto-r 25. In this connection, it will be recognized that the electric leads 30 extending to the motor 25 run through the reversing switch carried by the block 27.

Accordingly, the block 27 will move from end to end of the shaft 23 as it is driven in alternate directions, and the film strip 7 will be given a spiral scanning action inwardly and outwardly and inwardly, etc. with relation to the instantaneous radar image on the screen 4. Inasmuch as thel airplane is held against radical departure from its course by means of the automatic pilot, and is at all times at least substantially parallel with the course, the scanning action described will result substantially in a matchingY of the instantaneous radar image on the screen 4 and the strip radar image on the film 7.

. The images to be matched are made so that at the time of the match a maximum or a minimum amount of light will go through the matched images from the light source 6. One convenient Way to accomplish this result` is to make theA radar image o n the screen 4 either a positive or a negative, and to make the stripradar image on the film 7 just the opposite. I n other words, if the instantaneous radar image on the screen 4 is positive, then the radar image on the film strip 7 is made negative so at the time of match a minimum amount of light will flow through the matched images.

In order to pick oli the minimum, or the maximum, if this should be the case, one or more photo-electric cells 31 are mounted on the frame 13, and these photo-electric cells, which may be connected either in series or in parallel, extend to the input of an amplifier 32 connected to a power source by electric leads 33. The outputof the amplifier 32 extends to a solenoid tripping device 34 mounted on the block 27.

The construction of the solenoid tripping device 34 carried by the block 27 is such that it will not operate until the minimum voltage condition is experienced by the photo-electric cells 31, this condition being either a voltage drop beyond a selected magnitude, or a voltage drop over a definite period of time. In FIG. 3 is diagrammatically'illustrated the type of curve obtained byV plotting voltage against time during the scanning or matching efforts between the screen 4 and the film strip 7. The numeral 35 indicates a typ-ical drop in voltage as occasioned by a matching of positive and negative images on the screen 4 and film strip 7. When this match occurs as detected by the photo-electric cells 31, the solenoid trip device 34, in response either to the voltage drop or the time Iinterval of the drop, will drive a plunger sharply downward to punch a key, namely, one of the keys identified by the numerals 36 to 71.

In FIG. 6, I have shown the bottom end of the plunger 72 which is adapted to be driven downwardly by the trip solenoid 34. In order to prevent the plunger 72 from striking two keys at once, the keys are formed with notches 73, and with inverted fixed tapered guides 74. The bottom of the plunger 72 is formed with a pivoted extension 75 which is normally held in alignment with the plunger 72 by springs 76 carried between fixed lugs 77 on the plunger and lugs 78 afiixed to the extension 75. In this manner, as the plunger 72 is driven sharply downward by the solenoid 34, the extension 75 of the plunger will always drop into engagement with one of the keys 36 to 71 to punch this key.

Now, referring to FIG. 2 of the drawingsV in which the numerals 36 to 71 likewise appear, it will be evident that when the block 27 is in -a certain position on :the shaft 23 so that a given key, for example, key 57a, is punched, that the cam follower 21 will be substantially at the position 57 in the cam track 22, and the position in the scan- Y ning action, at the point of match of the instantaneous radar image and the strip radar map will be known. In FIG. 2, the spiral scanning path has been marked with appropriate designations, namely, the upper half of the scanning path is marked with the notation-SpeedV UpV Film Strip-and all points or keys lying in this half of the scanning path will require the speeding up of the motor 10 to speed up the movement of the film strip 7.. On the other hand, the lower half of the scanning path is marked with the notation-Slow Down Film Stripand all points or keys in this half of the scanning path will; require the slowing down of the motor 10 and the lnr strip7. v

In like manner, the left half of the scanning path shown4 in FIG. 2 is marked with notation-Left Rudderand all scanning points or keys in this half of the scanning path will necessitate the application of left rudder to bring the airplane back substantially exactly on course.

In a like manner, the right hand half of the scanning path of FIG. 2 is marked with the notation-Right Rudderl` and all keys in this half will result in the application of arenoso corrective right rudder to bring the airplane back on proper course.

Considering the arrangement of the parts more specilically, particularly with respect to the manner of correcting the course of the airplane, in FIG. l is illustrated a single relay 57h, it being understood that the relay 57a is actuated when key 57 is punched. From FlG. 2, it will be sec that point 57a is in the right rudder half and slow down lrn strip half of the relative scanning movement. Relay 57 actuates a time `and direction `relay titl which gives a predetermined shot of electric current to an electric motor Si which drives through gearing 82 to screw a threaded shalt to the right, the threaded shaft 33 being connected to the arm of the rheostat lll so that the motor lil is slowed down a given amount to thereby allow the airplane to catch up with the movement of the Hlm strip 7.

It is to be understood in this connection that punching the key 57h, and thus operating the relay 57, which in turn opera-tes its own time and direction relay do, will move the rheostat arm a somewhat greater distance and reduce the speed of the motor l@ a somewhat greater amount than if the plunger of the solenoid 34 had punched key 4S. in order words, the key 45 would operate its '-.vn relay which in turn would operate its own time selector and direction relay to slow down the speed of the lm strip 7, but the point 45 being closer to the horizontal, center line 6l67 of the scanning path shown in HG. 2 would not reduce the speed of the film strip quite as much as when the key 57 is punched. ln `a like manner, when the key dit is punched, it will operate through its own relays as described to reduce the speed of the iilm strip still more than when the key 57 is punched.

Furthermore, punching the key 57h to operate the relay S7 not only operates the relay titl 'to reduce the speed of the strip '71?, but in addition, operates a time selector and direction relay @il which extends to a solenoid valve 85 mounted on a `pressure cylinder or servo motor 86. The solenoid valve controls the flow of pressure iluid from a line 7 to the pressure cylinder or motor Se. '.i" he pressure cylinder de is adapted to act as a servo motor to control the position of a control surface S3, such as the rudder, on the airplane, and the operation of the relay de gives a selected amount of right rudder to the airplane for a period of time determined by the relay 8d. The point S7@ being relatively close to the neutral or vertical center line marked by the point lte-lila means that the right rudder applied by the relay Sli will be for a shorter time interval than if the key 6% had been struck to work through its own relay system.

Although the invention has only illustrated the relays 35i and ed controlled by an individual master relay 57h, it will be recognized that one or more additional relays may be incorporated to be controlled by the master key relay, to provide additional control functions on the airplane, such as the control ot the elevators, although this is usually not necessary or advisable. lt will be understood, also, that each key 36 to 7l will control the operation ol its own master relay, which will in turn control the operation of individual relays which operate upon the motor lll or the servo pressure cylinder So. In order to reduce weight, it may be possible to combine the functions of at least certain of the relays di? and 84 on more than one lacy, the master key rel ys controlling the selection of the appropriate operating relays.

in FlGS. 4 and 5 have been illustrated typical flight paths for an airplane controlled by the apparatus ot the present invention. ln FIG. 4, the airplane will take oit from the point marked, will climb over the path of the dott-ed line and will then follow a substantially level flight path indicated by the solid line gli, the airplane being controlled only during movement along the solid path line 0n the other hand, it is possible to control an airplane or other body in a curved flight path or pattern, as

el indicated by the solid line 91 of FIG. 5 all the way from take-oilc to landing point.

Having reference to FlG. 7 of the drawings, a moditication oi the invention has been illustrated in which the numeral 92 indicates a substantially conventional oscilloscope provided with associated apparatus for reproducing upon `the screen 93 thereof `an instantaneous radar image. A flexible hood @4 extends from the screen 93 to a lens system 95, and a eXible hood 96 extends from the lens system into close proximity with a lrn strip- 97 mounted in front of a bank 9S of photo-electric cells, the output of the cells being connected lto an arnplitier 99.

ln this arrangement of parts, the oscilloscope 92 and the support tor the film strip W, can be kept stationary, and the lens 95 can be moved to effect the scanning action. To this end, the lens system 95 is resiliently mounted upon springs lll-i) and lill, and a rod lili extending rigidly from the lens system is provided with a cam follower' lil?) which is received in a spirally cut cam groove in a circular plate ldd. The circular plate lld is mounted on the end of a shaft ltlS ,iournaled in bearings lilo. The drive and general arrangement of the circular plate 194 and the shaft ldd is similar to the plate 2li and shaft 23 heretofore described in conjunction with FlG. l, the result being that the lens system 95 is given a spiral movement so that the image from the screen 93 ellectively scans the film strip Q7 until a match is `effected at which time the photoelectric cells 93 serve to actuate the amplier 99 to control the operation or" keys and relays of the type heretotore described in conjunction with FIG. 1.

Also, in this embodiment of the invention the iilm strip 97 may comprise a series of previously prepared actual or simulatedv pictures or frames of the terrain over which the body is moving with the strip being moved ahead in jumps, like a motion picture film, raither than moved at the same constant speed. The word moved as employed in the specification and claims is intended to cover either the jump type movement or the continu- 'ous movement, and the word iilm is intended to cover either a continuous map or a series of map frames or pictures as long as the frames or pictures are advanced in turn to matching position.

The terms map, picture, image, as employed in the specification and claims are intended to cover a reasonable range of equivalents whereby information regarding the course and taken when flying over the course is compared with previously recorded or prepared information 'of the same course or terrain.

The invention of the present application is being referred 'to as atran, which is taken from the Words automatic terrain recognition and navigation.

From the foregoing, it will be recognized that the various `objects of the invention have been achieved by the provision of improved methods and apparatus for controlling movement of various bodies over a Wide variety of courses and conditions.

While in accord with the patent statutes, the invention has been specilically illustrated and described with respect to particular embodiment thereof, it is to be particularly understood that the invention is not tot be limited thereto or thereby, but that its scope is dened in the appended claims.

What is claimed is:

1. In combination, a film bearing a map image of a stretch of terrain over which a body is to move, motor means for moving the ilm, means for producing la substantially instantaneous image of the terrain over which the body is moving, said instantaneous image being of substantially the same scale and orientation as the map image and being superimposed upon the map image, means for etieoting periodically repeated scanning movement between the superimposed images, means for determining the position of match between the images, and means responsive to the match determining means for 7 controlling a direction of movement of the body in response to the position of match of the images.

2. In combination, a body, means for moving the body,

means bearing" a map image of a stretch of terrain over which the body is tlmove, motor means for advancing the map image substantially in accord with the speed of movement of the body, means for producing a substantially instantaneous image of the terrain over which the body is moving, said instantaneous image being of substantially the same scale and orientation .the inap image and being superimposed upon the map irriag, mn's for ef'- fecting periodically repeated scanning movement between the superimposed images, means for determining the position-of match between theimages, means forV varying the speed of the motor means in response to the position of match of the images, and means for controlling a direction of movement of the body in response to the position of match of fthe images.

3. In combination, a strip nlm bearing a'radar map of a stretch of terrain over which a body is to move, motor means for advancing the film, means for continuously presenting an instantaneous radar image of the terrain over which the body is moving, said radar image being of substantially the same scale and orientation as the map image and being superimposed upon the map image, means for effecting periodically repeated scanning movement between the superimposed images, means for indicating a match between the images, means for controlling a direction of movement of the body in response to the position of match of the images.

` 4. In combination, a strip iilm bearing a radar map of a stretch of terrain over which a body is to move, motor means for continuously unwinding the film, means for continuously presenting an instantaneous radar image of the terrain over which the body is moving, said radar image and map being substantially to the same scale and orientation means eiectingrelative superimposement of the radar and map images, means for eifecting periodically repeated scanning movement between the superimposed images, means for indicating a position of match between the images, means responsive to the last-named means for varying the speed of the motor means in response to the position of match of the images, and means responsive to the match indicating means for controlling a direction of movement of the body in response to the position of match of the images.

5. Apparatus for automatically guiding an airplane or the like over a stretch of terrain, the apparatus including an oscilloscope for reproducing an instantaneous radar image, a lm strip bearing a radar map of the terrain over which the airplane is to pass said image and map having substantially the same scale land orientation, motor means advancing the film `strip map substantially at a speed to coordinate lthe movement of the map with the passage of the airplane over the terrain, means mounting the iilm strip map for relative superimposed movement with respect to the instantaneous radar image, means for effecting a spiral scanning movement between the film strip map and the radar image, means for indicating substantially a match between the radar image and the map, push button means operated by the last-named means land coordinated with the scanning means, relay means operated by the push button means, prime mover means controlled by the relay means, and means operated by the prime mover means for changing the position for a selected time interval of a control surface on the airplane.

6. Automatic guidance mechanism for airplanes or other vehicles or bodies including a film strip bearing a mapY image of the course to be followed, means for moving the film strip image, means for producing a substantially instantaneous image of the terrain over which the airplane is passing, said images having substantially the same scale and orientation, a lens system for superimposing said images and for effecting a scanning action therebetween, photoelectric cell means for indicating a match between the images, mean-s controlled bythe photoelectric cell means for changing the speed of movement ofi the means for moving the iilm strip image, and means controlled by the photo-electric cell means for deflecting a control surface on the airplane for a time interval substantially suicient 'to bring the airplane fully on course.

7. That method of guiding an airplane or other body over a course which includes the steps of comparing a substantially instantaneous picture of the course with a previously prepared picture of `the course, eifeoting scanning movement of the pictures to effect substantially a match thereof, moving the prepared picture, and coordinating the speed of movement of the prepared picture to the Speeder movementofr-the body.V

8. That method of guiding an airplane or other body over a course which includes the steps of comparing a substantially instantaneous picture of the course with a previously prepared picture of the course, effecting scanning movement of the pictures to effect substantially a match thereof, and correcting the guiding controls on the body'in response to the substantial matching position of the pictures to bring the body back to substantially the center of its on-course position.

9. Mechanism for guiding a body in its movement over a course including a means for providing an instantaneous radar image of the course over which the body is moving, a strip radar map image of the desired course, means unwinding 'the map substantially in accord with the speed of movement of the body, means for superimposing the images, means having a spiral camway and including a motor for moving the images in a spiral path relative to each other, said last-named means having a helical camway :associateed therewith, a block movable from one end to the other of the helical camway, means for automatically reversing the motor as the block nears the end of its travel, a solenoid carried by the block, a series of push buttons positioned beneath the line of travel of the solenoid, means responsive to substantially a match of the images to operate the solenoid to actuate a push button beneath the solenoid, -a relay system associated with each push button, means controlled by the relay system to change the speed of movement of the map unwinding means, and means controlled by the relay system to correct the movement of the body to return it to substantially on-course position.

l0. Mechanism for guiding a body in its movement over a course including a means for providing an instantaneous radar image of the course over which the body is moving,V

la strip radar map image of the desired course, means unwinding the map substantially in accord with the speed of movement of the body, means for superimposing the images, means having a spiral camway and including a motor for moving the images in a spiral path relative to each other, said last-named means having a helical camway associated therewith, a block movable from one end to the other of the helical camway, means for automatically reversing the motor as the block nears the end of its travel, a solenoid carried by the block, a series of push buttons positioned beneath the line of travel of the solenoid, means responsive Ito substantially a match of the images to operate the solenoid to actuate ya push button beneath the solenoid, a relay system associated with each pushbutton, and means controlled by the relay system to correct the movement of the body to return it to substantially on-course position.

11. Apparatus for automatically guiding -an airplane or :the like including means for producing a radar picture of a portion of the terrain over which the airplane is ying, a previously prepared radar map of the terrain to substantially the same scale and orientation as the picture, a lens system superimposing the map and picture, means for moving the lens system to effect a scanning movement between the map and picture, means responsive to substantially a match between the map and picture, and means initiated by the last-named means and controlled by the 9 position of the lens moving means for returning the airplane to its proper course.

12. That method of guiding an airplane or other body over a `course which includes the steps of superimposing an instantaneous radar picture of the course upon a strip radar picture of the course, said radar and strip pictures being substantially similarly oriented and tothe same scale, eleoting scanning movement of the pictures to elect substantially a match thereof, continuously moving the strip picture, coordinating the speed of movement of the strip picture to lthe speed of movement of the body, and

correcting the guiding controls on the body in respense to the matching position of the pictures to bring the body back to substantially the center of its on-course position.

References Cited in the file of this patent UNITED STATES PATENTS 1,747,664 Droitcour Feb. 18, 1930 2,027,527 Hammond Jan. 14, 1936 2,027,530 Hammond Jan. 14, 1936 2,307,029 Elm Jan. 5, 1943 2,428,427 Loughren Oct. 7, 1947 

3. IN COMBINATION, A STRIP FILM BEARING A RADAR MAP OF A STRETCH OF TERRAIN OVER WHICH A BODY IS TO MOVE, MOTOR MEANS FOR ADVANCING THE FILM, MEANS FOR CONTINUOUSLY PRESENTING AN INSTANTANEOUS RADAR IMAGE OF THE TERRAIN OVER WHICH THE BODY IS MOVING, SAID RADAR IMAGE OF THE TERRAIN SUBSTANTIALLY THE SAME SCALE AND ORIENTATION AS THE MAP IMAGE AND BEING SUPERIMPOSED UPON THE MAP IMAGE, MEANS FOR EFFECTING PERIODICALLY REPEATED SCANNING MOVEMENT BETWEEN THE SUPERIMPOSED IMAGES, MEANS FOR INDICATING A MATCH BETWEEN THE IMAGES, MEANS FOR CONTROLLING A DIRECTION OF MOVEMENT OF THE BODY IN RESPONSE TO THE POSITION OF MATCH OF THE IMAGES.
 7. THAT METHOD OF GUIDING AN AIRPLANE OR OTHER BODY OVER A COURSE WHICH INCLUDES THE STEPS OF COMPARING A SUBSTANTIALLY INSTANTANEOUS PICTURE OF THE COURSE WITH A PREVIOUSLY PREPARED PICTURE OF THE COURSE, EFFECTING SCANNING MOVEMENT OF THE PICTURES TO EFFECT SUBSTANTIALLY A MATCH THEREOF, MOVING THE PREPARED PICTURE AND COORDINATING THE SPEED OF MOVEMENT OF THE PREPARED PICTURE TO THE SPEED OF MOVEMENT OF THE BODY. 